Deformation switch mechanism



R. G. 'rowLE 2,790,863

DEFORMAT-ION SWITCH MECHANISM I 2 Sheets-Sheet 1 April- 3o, 1957 Filed/'July 20, 1954 April 30, 1957 R: G.' rc w1 |s 2,790,863

DEFORMATION SWITCH MECHANISM Filed .July 2o, 1954 2 'sheets-sneer 2 INVENTOR BY' Afm ATTQRNEY United States Patent O DEFORMATION SWITCH MECHANISM Robert G. Towle, New City, N. Y., assignor to Specialties Development Corporation, Belleville, N. I., a corporation of New Jersey Application July 20, 1954, Serial No. 444,484

7 Claims. (Cl. 200--61.08)

This invention rela-tes to electrical circuit makers, and, more particularly, to switches which are operable by bhe deformation or severance of an elongate structural member.

Heretofore, it has been proposed to provide aircraft, for example, with systems which are automatically operable in the event of a crash to prevent explosions or breaking out of tire. In the provision of such systems, it is necessary that initiating means be able to sense a crash as ydistinguished from other less violent occurrences such as storms and the like, as well as from malfunction of components of the system itself. Such systems are therefore operated by the actuation of a plurality of switches simultaneously, each of which responds to a different condition which has been found to occur during a crash.

Careful .study of crashes reveals that explosion or fire is often caused by gasoline, oil, or other combustibles, which are usually carried in the wings, escaping from damaged containers or conduits and coming into contact with hot engine parts.

Accordingly, it is an object of the present invention to provide a switch mechanism which is adapted to close an electrical circuit in the event of the deformation, beyond a predetermined limit, or breaking olf of a wing or other structure of considerable length.

It is another object to provide such apparatus ineluding an initiating cable extending lengthwise along the length of the structure subject to deformation or breaking ott' in the event of a crash.

It is another object to provide such apparatuswherein the cable will be rel-eased from the other switch components when deformation of the cable occurs which is great enough to damage such other components.

lt is a further object of the present invention to provide such apparatus which is reliable and eicient in operation, easily installed in an aircraft, light in weight, requires very little maintenance, is free from damage by the elements yand has a long shelf life.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In accordance with the present invention the foregoing objects are accomplished by providing craft having a structure of considerable length subject to being deformed or breaking oft" upon crash of the craft with switch japparatus comprising a pull cable extending lengthwise along the structure having one end secured to the structure adjacent one end thereof, spring means adjacent the other end of the structure for exerting a force on the pull cable at the other end thereof to tension the same, actuating means, and an element movable with the pull cable for effecting operation of the actuating means upon a change in the tensioni-ng of the pull cable.

ICC

A preferred embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawing, forming a part of the specification, wherein:

Fig. 1 is a longitudinal fragmentary view partly in section, of apparatus in accordance with the present invention connected to one end of the cable;

Fig. 2 is a longitudinal view, partly in section, of apparatus connected to the other end of the cable;

Fig. 3 is a view similar to Fig. l but shows another embodiment of the invention; and

Fig. 4 is a view similar to Fig. 2 but shows another embodiment of the apparatus illustrated therein.

Referring to the drawings in detail, there is shown in Fig. 1 a frame or casing 10 supporting a conventional lswitch 11 and being formed with a pair of opposite apertures 12 and 14 in the ends thereof. Slide bearings 15 and 16 are mounted in the respective apertures 12 and 14, a rod 17 is slidably mounted in the bearings for operating the switch, a helical compression spring 19 is arranged for urging the rod in one direction, and a pull cable 20 is connected at one end to the rod for effecting movement thereof in opposition to the spring.

The switch 11 is provided with an actuating plunger 21 and an operating arm 22, formed preferably of spring steel, secured at one end to the switch body and positioned over the plunger at its other end. A roller 24 is mounted at the free Iend of the arm and is normally urged by the spring action thereof in a direction away from the plunger 21.

The ends of the rod 17 extend outwardly through the bearings 15 and 16, and the portion of the rod which is normally disposed within the casing is formed with a section 25 of reduced diameter having frusta-conical cam faces 26 and 27 at the respective ends for actuating the switch as described hereinafter.

rPhe end of the rod to which the cable 20 is connected is provided with an axial slot and a radial bore adapted to serve as a clevis joint 29 for the reception of a at tongue 30 of a swage element 31 for retaining the end of the pull cable 20. The clevis pin 32 is adapted to shear when the cable is placed under a predetermined tension. An annular snap ring 33 is seated in a groove in the rod adjacent the clevis joint for a purpose to be described.

The opposite or free end of the rod is formed with an .annular groove for seating a snap ring 34 which serves as a backing for a washer 35 and the spring 19 fits over the rod 20 and the tubular slide bearings 16 and bears against an annular flange 18 of the bearings at one end and against the washer 35 at the other end to urge the rod 20 to the left, as viewed in Fig. 1.

A tubular sleeve member 36 is screw threadedly secured to the slide bearing 15 at one end and to a fitting 37 formed with a longitudinal bore 39 at the other end and serves to protect the clevis joint 29 and the swage element 31 against damage from external sources.

As shown in Fig. 2, the other end of the cable 2i) is anchored in a mount 40 which may be located any desired distance from the actuating mechanism described heretofore. In order to protect the cable against injury or wear by contact with structural members of the craft, a tube 41 surrounds the cable and is tted into the bore 39 at one end, in sliding engagement with the fitting 37, while the other end of the tube is secured in the mount 4i) substantially at the other end of the cable so that no portion of the cable is exposed.

The mount 40 includes a tubular member 42 formed with apertured flanges for securement to the craft, a fitting 44 formed with an axial bore secured in one end thereof, a second fitting 45 formed with an axial bore arenaria secured in the other end thereof and a hollow cable rctaining bloeit 46 open at one end and provided with an aperture 43 at the other end slidably and adjustably disposed within the member 42 between the end fittings.

The cable 20 passes through the bore in the tting 44 and the aperture in the block 46 in which it is secured and thc tube 41 is flared at its end and abuts the fitting 44 to which it is secured by a conventional tube nut 47 and sleeve clamp 48.

A stud 49 threaded at one end extends through the bore of the iitting 45 and is secured at lits other end to the Open end of the block by a clevis joint 52. A nut 51 screw threaded on the stud serves to adjust the cable in a manner to be described.

To mount the apparatus to actuate the switch upon de formation or breaking off of a wing of an aircraft, for example, the casing may be mounted adjacent the inboard end of a wing, say in the wheel well. and the mount 40 may be secured to a structural member of the Wing at its outboard end in such a manner that the cable extends substantially adjacent and parallel to the leading edge of the wing. The position of the rod 17 is then adjusted by means of the stud 49 in the adjusting mount so that the roller 24 abuts the section 25 of thc rod at its center. In order to determine when center contact is established without removing the cover of the casing, indicia, such as an annular groove may be provided on the rod so that it lines up with the end of the slide bearing 16 when the proper adjustment is effected.

ln operation, normal deflection of the wing, due to vibration, wind currents and the like, will not actuate the switch l1 due to the predetermined length of the section 25 of the rod 17 which will merely move back and forth over the roller 24. flection occurs, due to a collision or crash, for example, the cable will be deformed so as to pull the rod in a direction towards the mount 40 to such an extent that the cam face 26 will bear against the roller 24 and cause the arm 22 to depress the switch plunger 21 to close an electrical circuit.

If the cable is deformed to a point such that the shear load on the clevis pin 32 is greater than that for which it is designed, the pin will shear disconnecting the cable from the rod to protect the casing and switch from being damaged. On the other hand, in the event that a portion of the wing and consequently the cable, is sheared of.F by a relatively sharp object, say, for example, a wire, the spring 19 will urge the rnd in a direction away from the mount 40 until the cam face 27 bears against the roller 24 causing actuation of the switch in the manner described. The annular ring 33 will engage the end of. the slide bearing 15 to prevent the rod from being moved completely out of the casing by the spring.

In Fig. 3, an. embodiment of the present invention is illustrated wherein adjustment is made at the switch end ofthe cable and a moisture proof casing is provided to prevent corrosion of the parts whereby a long shelf and operating life is assured.

The casing 55 is essentially the same as that described heretofore except that slide bearings 56 and 57 are formed integral with the casing and project outwardly away from the end walls thereof while surrounding apertures 59 and 60, respectively. The casing cover plate (not shown) is provided with a moisture proof gasket and the switch and its actuating lever and roller are disposed in the casing in the manner described hereinbefore.

A rod 61 extends through the casing and is in slidable engagement at one end thereof with the bearing 56. This rod is formed with a section of reduced diameter 62 having carn faces 64 and 65. The end portion of the rod extending out of the casing through the aperture 59 is formed with an end slot 66 and a groove 63. The other end of the rod 61 is provided with an internally threaded axial bore 67 and an external flange 69. The

However, if abnormal dej rod 61 is considerably shorter than the rod 17 discussed heretofore and does not extend through the bearing 57 when in its normal position, as viewed.

To assist in preventing moisture from entering the cas-A ing, a cap 68 is in screw threaded engagement with the outer surface of the projecting portion of the bearing 56 and covers the slotted end of the rod 61, allowing sufficient clearance for the rod to move to the right, as viewed, to enable the cam face to eifect actuation of the switch. At the other side of the casing, the projecting portion of the bearing 57 is externally screw threaded to receive an elongate sleeve member 70 formed with a longitudinal bore 71 therethrough providing an internal shoulder 72.

One end of a tube 74 for protecting the cable extends into the end of the bore 71 in the sleeve member and is slidably disposed therein.

An adjuster rod 75 provided with a longitudinal slot 76 is slidably mounted at one end in the tube 74 and extends into the bore 67 of the rod 61 with which it is in screw threaded engagement. The end of the adjuster rod which is mounted in the tube is provided with a clevis joint, including a clevis pin adapted to shear under a predetermined load, by which a swage element is secured in the manner described heretofore. Gne end of the cable is retained by the swage element and the cable and tube extend any desired distance to an end mount 82, as shown in Fig. 4.

A tubular spring retainer 77 surrounds the adjuster rod and `is formed with an end flange 79 abutting the shoulder 72 of the sleeve member 70. The other end of the retainer has a radial bore from which a pin 80, secured therein7 extends into the groove 76 of the adjuster rod to prevent the rod from rotating.

A helical spring 81 extends between the ange 79 of the spring retainer and the flange 69 of the rod 61 and tends to urge the rod in a direction away from the retainer.

As shown in Fig. 4, the end mount 82 includes a block 84 formed with a bore 85 having an internal shoulder 86 extending therethrough. A standard titting 87 is threaded into one end of the bore and the cable passes through the fitting and is soldered to an anchor member 89 provided with a ilange which abuts the shoulder 86 to anchor the end of the cable in the block. The other end of the fitting S7 is secured to a conventional tube nut and sleeve clamp for securing the end of the tube 74 in the manner described with respect to Fig. 2 and the open end of the bore is sealed by a plug 90 fitted with a conventional gasket.

In this embodiment of the invention, conventional O-rings 91 are employed as seals against moisture at the threaded end of the cap 68, at both ends of the sleeve member 70 and between the fitting 87 and the block 84.

ln order to adjust the position of the rod 61, the cap 68 is removed and, by means of a screw driver applied to the slot 66, the rod may be rotated until an annular groove lines up with the end of the projecting portion of the bearing 56 in the manner described heretofore. The rod may be locked in this position by sliding a locking ring 92 having an internal tab and a pair of opposite external tabs `over the rod so that the internal tab tits into the groove 63 and the external tabs are then bent into longitudinal external grooves in the projecting portion of the bearing.

As the rod 61 is rotated, the adjuster rod 75 is moved into or out of the bore 67 since the pin 80 mounted in the spring retainer 77 and extending into the `groove 76 of the adjuster rod prevents that rod from rotating.

The apparatus illustrated in Figs. 3 and 4 is similar in operation to that described heretofore. Deflection of the cable beyond a predetermined limit will cause the rod to move against the action of the spring 81 until the cam faceA 64 effects operation of the switch. Severance of the cable will cause the spring to urge the rod in a direction whereby the cam face 65 will effect operation of the switch. The cap 68 serves to prevent the rod from being ejected out of the casing entirely in the event that the clevis pin is sheared by excessive tension applied to the cable.

From the foregoing description, it will be seen that the present invention provides a switch mechanism for closing an electrical circuit in the event of deformation, beyond a predetermined limit, or breaking off of a wing or other `structure of considerable length, which mechanism is reliable and efficient lin operation, easily installed, light in weight, requires little maintenance, is free from damage by the elements and has a long shelf life. It will also be seen that the apparatus includes a cable extending the length of the structure subject to deformation or breaking off which cable will be released from the other components of the apparatus before deformat-ion of the cable occurs which is great enough to damage the other components thereof.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

I claim:

l. In combination with craft of the class described having structure of considerable length subject to being deformed or breaking off upon crash of the craft, a pull cable extending lengthwise along the structure having one end secured to the structure adjacent one end thereof, actuating means adjacent the other end of the structure, an element having the other end of said pull cable connected to one end thereof, a spring connected to the structure and to the other end of said element for tensioning said pull cable, and means on said element for effecting operation of said actuating means upon an increase in the tensioning of said pull cable, and upon failure `of said cable said pull cable and said element being connected by a pin adapted to rupture when an excessive force is exerted on said pull cable.

2. In combination with craft of the class described having structure of considerable length subject to being deformed or breaking off upon crash of the craft, a pull cable extending lengthwise along the structure having one end secured to the structure adjacent one end thereof, a switch adjacent the `other end of the structure having an operating aim, a slidably mounted element adjacent said switch and connected to the other end of said pull cable at one end thereof, and a spring connected to the other end of said element for tensioning said pull cable, said element being constructed and arranged for movement in a direction towards said cable upon an increase in the tension thereof and for movement in the opposite direction under the influence of said spring upon failure of said cable and having means for engaging said arm upon movement thereof upon an increase in the tension of said cable and having means for engaging said arm upon failure of said pull cable and movement of said element under the influence of said spring.

3. In combination with craft of the class described having structure `of considerable length subject to being deformed or breaking off upon crash of the craft, a pull cable extending lengthwise along the structure having one end secured to the structure adjacent one end thereof, a switch adjacent the other end of the structure having an operating arm, a slidably mounted element adjacent said switch and connected to the other end of said pull cable at one end thereof, and a `spr-ing connected to the other end of said element for tensioning said pull cable, said element having means for engaging said arm upon pulling of said cable and having means for engaging said arm upon failure of said pull cable and movement of said element under the influence of said spring, sa-id element and said pull cable being connected by a pin adapted to rupture when said pull cable is tensioned beyond a predetermined value, whereby said element is free to move under the inliuence of said spring.

4. A control head of the class described comprising a frame for means to be actuated, said frame having aligned slide bearing means at opposite sides thereof, an element slidably mounted in said bearing means and extending through said frame, said element having a pair of spaced apart portions for actuating the first mentioned means, a spring for urging said element in one direction, a pull cable connected at one end to said element for effecting movement thereof in opposition to said spring and being fixed at its other end, and stop means for limiting the movement of said element under the iniiuence of said spring, said element and said pull cable being connected by a pin adapted to rupture when said pull cable is tensioned beyond a predetermined value, whereby said element is free to move under the influence of said spring.

5. A control head of the class described comprising a frame for means to be actuated, said frame having aligned bearings at opposite sides thereof and having stop means adjacent one of said bearings, a rod slidably mounted in said bearings and extending through said frame, said rod having a reduced intermediate section providing a pair of opposed faces for actuating the first mentioned means, a pull cable fixed at one end thereof, means including a rupturable element for connecting the other end of said pull cable to one end of said rod, a spring retainer on said rod adjacent the other end thereof, a cylindrical helical spring suirounding said rod and compressed between said retainer and said frame to urge said rod in a direction to tension said pull cable, and means for varying the effective length of said pull cable to arrange said rod faces in a neutral position with respect to the first mentioned means.

6. A control head of the class described comprising a frame for means to be actuated, said frame having aligned bearings at opposite sides thereof and having stop means adjacent one of said bearings a rod slidably mounted in said bearings and extending through said frame, said rod having a reduced intermediate section providing a pair of opposed faces for actuating the first mentioned means, a pull cable fixed at one end thereof, means including a rupturable element for connecting the other end of said pull cable to one end of said rod, a spring retainer on said rod adjacent the other end thereof, a cylindrical helical spring surrounding said rod and compressed between said retainer and said frame to urge said rod in a direction to tension said pull cable, means for varying the effective length of said pull cable to arrange said rod faces in a neutral position with respect to the first mentioned means, and means for adjusting the position of said spring retainer to vary the force of said spring acting to tension said pull cable.

7. A control head of the class described comprising a casing for means to be actuated, said casing having aligned slide bearing means at opposite sides thereof, an element slidably mounted in said bearing means and extending through said casing, said element having a pair of spaced apart portions for actuating the first mentioned means, a spring for urging said element in one direction, a pull cable releasably connected at one end to said element for effecting movement thereof in opposition to said spring and being fixed at its other end in a mount sealed from the ambient atmosphere, tube means substantially coextensive with said cable and surrounding the same, sleeve means abutting said casing and sur- References Cited in the file of this patent UNITED STATES PATENTS Gruettner Oct. 4, 1927 Sarcione Oct. 5, 1937 Jennings Jan. 11, 1938 Framhein Apr. .13, 1954 

